Obesity Gene Trumped by Healthy Diet

With a Healthy Diet, Kids With Obesity Gene Not Destined to Be Fat

By Daniel J. DeNoon
WebMD Health News

Reviewed By Louise Chang, MD

March 5, 2009 -- Children born with a gene linked to obesity don't have to get fat. A healthy diet trumps the obesity gene's unhealthy effects.

People who inherit a variant version of the FTO gene tend to have to eat more to satisfy their appetites. As a result, they gain excess fat. That's why FTO has been dubbed the " obesity gene."

The seeds of obesity are planted early in life. But kids with the obesity gene are not doomed to be fat, says University College London researcher Laura Johnson, PhD, and colleagues. Children with the FTO variant aren't any more vulnerable than other kids to the fat-increasing effects of energy-dense, high-calorie foods.

"Obesity is not inevitable if your genes give you a higher risk," Johnson said in a news release. "Those with high-risk genes can, in some cases, resist their genetic lot if they alter their lifestyle in the right way -- in this case, their diet."

The findings reinforce what child obesity expert David S. Ludwig, MD, PhD, told WebMD last year.

"We know that genes affect our body weight set point. But so does our environment and our diet," Ludwig told WebMD. "We can't change our genes, but we can change our diet, and by doing so in a sophisticated way, we may be able to adjust that body weight set point in our favor."

Energy-Dense Foods, Children, and the Obesity Gene

Energy-dense foods, such as cheese, are dry and/or fatty. They contain more calories per bite than leaner, more watery foods such as soup.

Adults tend to eat the same amount of food, regardless of its energy density. Eating a diet rich in energy-dense foods increases obesity risk for grown-ups.

That's not true for kids, Johnson notes. When younger kids eat energy-dense foods, they generally eat less at the next meal. As they get older, though, they get more and more like adults.

Might the obesity gene make young children particularly vulnerable to energy-dense foods? It's an important question, as nearly one in five U.S. kids aged 6 to 11 years is overweight. So is nearly one in three British kids aged 10 to 11 years.

To get answers, Johnson's team looked at data collected during a long-term study of 2,275 children who were tested for the FTO gene.

Information on what the kids ate at age 10 was used to determine the energy density of their diets. Then the researchers looked at how much fat mass the children had accumulated by the time they reached age 13.

The 13-year-olds tended to be fatter if they had the FTO gene variant. And they tended to be fatter if they ate an energy-dense diet at age 10. But there was no sign that the obesity gene made energy-dense diets extra risky for children.

That, Johnson and colleagues conclude, means that kids can offset the risk of having the obesity gene if their parents feed them fewer energy-dense foods.

How? By doing what they're supposed to do anyway: Replacing high-fat foods with low-fat foods and giving kids more fruits and vegetables.

The study findings appear in the March 2009 issue of the online journal PloS One.

SOURCES: Johnson, L. PloS One, March 2009; vol 4: pp e4594. News release, University College London. WebMD Health News: "How the FTO Obesity Gene Works." David Ludwig, MD, PhD, director, obesity program, Children's Hospital, Boston; and associate professor of pediatrics, Harvard Medical School, Boston; interviewed Feb. 19, 2008 by Sandee Lamotte.

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